In the field of drug preparation for injection or infusion generally two basic problems have to be considered. Firstly, certain demands are made on aseptic conditions so as to avoid contamination of the drug, and, secondly, the drug has to be handled in such a way that drug leakage to the environment is prevented or minimized. By a sterile or aseptic handling of the drug, the risk for transferring bacteria or any other undesired substance to the patient is reduced. By preventing drug leakage to the environment, the exposure of medical and pharmacological staff to hazardous drugs is decreased.
In order to achieve aseptic conditions special safety boxes, cabinets or isolators are being used where the air is filtered through HEPA filters to prevent contamination during preparation of drugs. Ventilated cabinets are also used to reduce uncontrolled leakage to the environment and prevent occupational exposure to possibly hazardous drugs. Such facilities, however, require a lot of space and are associated with relatively high costs. Furthermore, the offered protection can be insufficient and working environment problems due to accidental exposure to drugs, for example cytotoxins, have been reported.
Another solution of the problems mentioned above is to create a so called “closed” or “non-vented” system for handling the drugs during preparation. Such systems exist and enable the preparation to be accomplished without the use of special clean rooms or fume cupboards. In such a closed system the drugs are handled isolated from the environment during every single step so as to avoid contamination of the drug and undesired drug leakage to the environment.
A known problem associated with the preparation of drug solutions is the fact that medical bottles or vials normally are made of a non-compressible material, such as glass or plastic. To enable the vial to be drained off, air has to flow into the vial so as to avoid negative pressure in the drug vial which negative pressure otherwise counteracts or prevents further transportation of liquid from the vial to another receptacle such as syringe.
Different systems for providing sterilised or cleaned gas are described for example in WO 00/35517 and WO 02/11794. However, these systems have drawbacks due to the number of manipulations to be accomplished and/or the requisite special equipment for providing the gas.
Within the field of medical devices very often any kind of needle for penetration is used. For example, hollow needles are used for penetration of a closing (which can be made of rubber for instance) covering an opening of a drug vial. Such injection needles or cannulae can be used for enabling gas or liquid transportation between a drug vial and another receptacle. The expression “piercing member” or “needle” used hereinafter is meant to comprise also spikes and similar components for penetration of such a closing in order to create a channel for the transportation of gas or liquid.
A medical device comprising such a needle has drawbacks because the person handling the device can due to incautiousness be injured by the needle. Furthermore, the package enclosing the device can be damaged by the needle during transport and storage of the device. To solve this problem such medical devices can be provided with a needle shield covering the tip of the needle, which shield functions as a protection during storage and the initial handling of the device.